I'm not sure how Scirra handles licensing exactly, but I do think that it handles it very well. If a user decided to release their license, then well, once the license is out there and being used amongst multiple computers suddenly, it can be blacklisted and no longer work if the user remains online (I think. I don't know if Scirra receives any data when someone uses a license file on a new IP address or anything).
I think piracy isn't a real threat. If, say a student, makes little income, and there's software they want (E.G Flash) that costs hundreds, they'll never really be able to pay for that anytime soon, so the company looses no money whether they can pirate or not. (And you've got to admit, the amount of people using Flash out there making animations, I somehow highly doubt that every single person began with a paid version)
Also, agreeing with 
CJK , having a company that makes a great product at a great price, or a band makes a great album and you've heard it beforehand to know how good it is, then the user would probably be more inclined to purchase it ultimately to support the developers (unless the person is insanely greedy, in which case, he'd find the cheapest way to acquire it for free regardless).
My most favourite thing about C2's license is, the cheapness, and the fact that the only requirement is that IF you make a tonne of quids, THEN you pay a small portion and that's it, you're free to continue (unlike shelling out ?600 and possibly never make that money back)
I'm rambling <img src="smileys/smiley20.gif" border="0" align="middle" />